Boucher,
Not sure if your exhaust manifold has an alignment tube that is about 2" or smaller? It is a restrictor IMO.
IIRC, my moms 73 Nova had one, I removed it & did some opening up on the exit of the exhaust manifold to breath better.
Could have been my 65 Malibu 283's manifolds?
You can do the same w/grinder & carbide tips to improve exhaust flow, won't cost anything, just your time.
Grind down any sharp edges & try & picture how you can make the exhaust flow better. A more straighter path.
I believe I mentioned to you before,, the wastegate's 90 degree exit from your turbine wheel is really restrictive & will cause your turbo to spool slow.
If you do ever change your downpipe, look into a straighter exit of the exhaust from the turbo. Also, make it a full 3" downpipe, it does make a difference on how fast the turbo spools up.
Even if you have only a 2" turbine wheel, the better flowing exhaust, no baffles in a muffler, etc, make for a quicker spooling turbo.
Only drawback of running 3" & larger downpipe, is it gets a little harder to quiet it down, but it can be done.
MBHD
